In a machine tool on which an NC unit (numerical control unit) is mounted, a work is machined into a desired product shape by executing the NC program. To create the NC creation program for creating the NC machining program, recently, an automatic programming technique using a microcomputer referred to as an automatic programming device has been frequently used.
The early automatic programming devices were not connected to the CAD data, and hence, it was necessary to perform programming, while watching the machining shape in a drawing or the like. However, recently, some techniques relating to the automatic programming device that creates the NC machining program by the CAD data have been proposed.
For example, in Patent Literature 1 (Japanese Patent Application Laid-Open No. 2002-189510), feature data of a machined product is extracted from the CAD data to set a machining process and a machining area for each machining process, material data and a machining model for each machining process are created, the created machining process data and machining model data are stored, tool path data is created based on the machining process data, material data, machining model data, tool data, and cutting condition data, to create virtual work shape data after completing the respective processes, as well as creating fabrication information based on the created process data, material data, tool path data, and virtual work shape data.
In Patent Literature 2 (Japanese Patent Application Laid-Open No. 2002-268718), when a machining path for machining a workpiece based on a three-dimensional CAD data of a part is created, machining information for all portions to be machined in a shape indicated by the three-dimensional CAD data is extracted, the extracted machining information is edited to determine a machining process, and the machining path is created based on the determined machining process.
The machine tool to be controlled by the automatic programming device includes a two-spindle machine tool having a first spindle (main spindle) and a second spindle (sub-spindle) installed so as to face the main spindle, and a one-spindle machine tool having only the main spindle. More efficient machining can be performed by using the two-spindle machine tool having the main spindle and the sub-spindle than by using the one-spindle machine tool, but some users have only the one-spindle machine tool.
Therefore, it is desired that the automatic programming device have a function of performing automatic process development with respect to users having only the one-spindle machine tool.
In Patent document 3 (Japanese Patent Application Laid-Open No. H2-62603), it is determined whether respective processing sites specified by an operator to be machined by any one of a first process performed by using the main spindle and a second process performed by using the sub-spindle can be machined only by the first process or the second process, or can be machined only through the first and the second processes, and machining is executed based on the determination result.
In the Patent document 3, however, it is only disclosed that the respective processing sites can be machined only by the first process or the second process, or can be machined only through the first and the second processes. Hence, automatic programming applicable to both of the one-spindle machine tool and the two-spindle machine tool cannot be executed according to the Patent document 5.
The present invention has been achieved in order to solve the above problems, and it is therefore an object of the invention to provide an automatic programming method and device that can be applied to any of the two-spindle machine tool having the main spindle and the sub-spindle, and the one-spindle machine tool having only the main spindle.